This invention relates to insulating sealed units and in particular to sealed units made from glass plates.
It is well known to construct a glass insulating sealed unit made from two or more spaced-apart sheets of glass with the glass plates being separated by spacers that are made to act as vapour seals or combined with such seals. The gas or air between the glass plates is made vapour free and generally a dessicant material is provided in or in the region of the spacers to maintain the moisture-free environment between the glass plates. It is necessary to maintain a moisture-free condition between the glass plates if the sealed unit is to be kept in a condition where condensation does not form and the unit can always brought to a very clear, transparent condition.
Various arrangements are known at the present time for mounting and supporting the sealed units in a framework or mullion without exterior stops or caps. The interior light or sheet of glass of the unit can be adhered to the structural mullion frame in situ or alternatively this light can be adhered to a framework in a factory and then the total combination can be clipped or bolted in place. Although it is preferable to adhere the inner light to the adjoining framework, it is also possible to adhere both the interior and exterior lights to the framework or just the exterior light. Generally a setting block is placed between the inner surface of the edge portion of the lights and the adjacent framework.
When the interior light is adhered directly to the mullion frame, all the wind and gravity loads acting on the unit pass through the adhesive sealant and, in the event of failure of this sealant, the whole unit can fall out of the frame. A further problem arises from the fact that there is no reliable method of determining whether the seal between the edges of the glass plates has failed.
Another problem with sealed units presently being sold is that the air or gas enclosed and sealed between the sheets of glass expands or contracts during the life of the unit due to temperature change, atmospheric pressure changes, outgassing of dessicant and/or environmental loads such as those caused by wind or snow. This expansion or contraction of the air in the unit can cause the glass to deflect. The deflection in turn produces stresses on the seals which can eventually result in their failure.
U.S. Pat. No. 3,981,111 issued Sept. 21, 1976 to N. T. L. Berthagen describes and illustrates an insulating unit wherein the glass plates are sealingly joined together around their peripheral edges by spacers which act as seals. The spacers are constructed to permit a pivoting movement of one of the transparent plates towards and away from the opposing plate, thereby to increase or decrease the volume of the enclosed gas or air in response to temperature changes.
Recent U.S. Pat. No. 4,348,435 issued Sept. 7, 1982 to PPG Industries Inc. teaches a multiple glazed unit having an organic elastomer sealant about its periphery. The unit is mounted into a curtainwall system by first coating the exposed organic elastomer sealant with a suitable primer before bonding the unit to the curtainwall system with silicone elastomer adhesive.
It is an object of the present invention to provide an insulating sealed unit that can be glazed without exterior stops or caps and that reduces the loads on the structural sealants by 50% or, in some cases, considerably more.
It is a further object of the invention to provide a glass insulating sealed unit wherein at least one of the lights of glass will be retained in place in the event of failure by the structural sealant and this will in turn maintain the integrity of the building envelope provided by the glass units.